Hydraulic lift for top of mobile living quarters

Abstract

A hydraulic lift for mobile living quarters having a liftable top. A fluid pressure source communicates fluid through fluid lines connected to a plurality of lifting members that extend upon receipt of fluid and retract upon discharging fluid. The rate at which fluid is discharged from the lifting members is a function of how much weight each lifting member bears. Each of the fluid lines has a flow control valve between the pressure source and each lifting member. Fluid is communicated through the flow control valve to the lifting member connected to the pressure source the fluid is also communicated through the flow control valve when fluid is discharged from the lifting member. The flow control valve limits the flow rate of the fluid to a constant predetermined rate when the fluid is discharged from the lifting member.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit and priority of U.S. Provisional Patent Application Ser. No. 60 / 806,677, filed Jul. 6, 2006, the subject matter of which is hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]Camping trailers have long been provided with lift mechanisms for raising and lowering the top. Some lifts use telescoping corner posts to accomplish this task.[0003]U.S. Pat. No. 3,363,932 uses a single pumping piston which supplies four separate hydraulic cylinders in four corner posts and has adjustable valves to allow each of the corner posts to descend at an equal rate to the other posts. The valves restrict the flow of fluid returning from the hydraulic cylinders in the corner posts, which adjusts the rate of descent for the cylinder in line with the adjustable valve. If the posts do not descend evenly, binding and excessive wear can occur. In use the weight of the camper top would almost never be evenly distri...

AI Technical Summary

Benefits of technology

[0004]The present invention is a liftable top for mobile living quarters. The top is supported by lifting members which are a piston retained in a cylinder. The lifting members extend when receiving fluid and retract when fluid is discharged from the lifting members. Fluid is discharged at a rate which is a function of the weight borne by the lifting member. A pump communicates fluid to the lifting members through fluid lines. Each fluid line connected to the lifting members has a flow control valve therein. Each line also has a release valve to allow fluid to be discharged from the lifting members. The release valves may be contained in the pump or in the fluid lines. In either case, the release valves are operated simultaneously to allow fluid to be discharged from the lifting members, thereby lowering the top. As the top lowers, flow control valves limit the fluid discharged from the lifting members to a predetermined flow rate. This causes the lifting members to lower the top evenly despite different weight borne by each lifting member.

Problems solved by technology

If the posts do not descend evenly, binding and excessive wear can occur.

If a user guessed wrong in his adjustment of one or more of the posts, the camper could bind due to an uneven rate of descent.

Also, if the weight distribution changed in any way due to different loading conditions, a user would have to readjust the valves.

It is unsafe and unreasonable to expect a consumer to properly adjust the valves each time the camper top is raised or lowered.

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